Ice formation may be undesirable on a variety of apparatuses that are exposed to atmospheric conditions. For instance, ice formation on aircraft may disturb the aerodynamics of airfoils, for example affecting laminar flow and weight distribution, and thus is generally regarded as undesirable.
Ice may form under icing conditions, i.e., atmospheric conditions in which the air contains droplets of supercooled liquid water. Icing conditions are characterized quantitatively by the average droplet size, the liquid water content of the air, the air temperature, and the temperature of exposed surfaces. Supercooled liquid water is water that is below the freezing point but still remains liquid. Normally, water would freeze at the freezing point but atmospheric droplets may remain liquid if, for example, the droplet has no contaminants to nucleate ice formation. When a supercooled water droplet encounters a cold surface, the droplet immediately solidifies and forms ice.
Typical solutions to resist ice formation include heating the exposed surfaces that are sensitive to ice, mechanically deforming a portion of the exposed surfaces, and applying a deicing fluid. Each of these solutions is an active mechanism, with the attendant burdens of control, monitoring, maintenance, and/or weight.
Icephobic surfaces typically are, or are designed similarly to, superhydrophobic surfaces and/or coatings and hence are relatively delicate. Such coatings and/or surfaces typically are not suitable for harsh environments where ice formation is common. Airfoils may experience even more extreme conditions, rendering existing icephobic solutions even less suitable.
Hence, there is a need for passive icephobic systems that resist ice formation in harsh environments.